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Posted on February 1, 2020 at 4:28 PM by Colin Keedy
What is Protein
One strand of protein is comprised of hundreds of small amino acids bound by peptide bonds. There are twenty types of amino acids; and, a protein may only be called complete when its string consists of every amino acid . Examples of complete proteins are: red meats, poultry, seafood, eggs, and dairy. For vegetarians and vegans, fewer examples exist: peanut butter, quinoa, seaweed, and buckwheat are some of the only options . Complete proteins are important because your body doesn’t create 9 amino acids, which are called the essential amino acids. You must consume these essential amino acids through an external source. Amino acids are necessary to counteract muscle protein breakdown (MPB) and facilitate muscle protein synthesis (MPS).
Balancing MPB and Boosting MPS
Muscle protein synthesis is the process of facilitating skeletal muscle adaptations as a response to physical exercise. The anabolic effects of nutrition are driven by the transfer of amino acids directly into skeletal muscle proteins: what we eat facilitates MPS and regulates, diminishes MPB [1, 2, 6]. The most effective way to increase MPS and diminish MPB following intense physical exercise is to consume essential amino acids; more specifically, the essential amino acid leucine is paramount for proper recovery and growth .
How MPS and MPB are Triggered
The two determinants of MPS are exercise intensity and nutrient availability [1, 6]. MPS increases after a difficult bout of physical exercise – reps at 70 to 90% of one rep max; also, MPB occurs: a negative amount of net protein synthesis, protein degradation and BCAA oxidation . Also, exhaustive endurance running reduces MPS significantly when compared to someone resting; recovery drinks with only glucose or sucrose don’t return MPS to a resting state, yet drinks with leucine only do . Although, resistance exercise is not shown to decrease MPS; it drastically increases MPB, which results in a significant net loss of protein synthesis . It remains negative until dietary protein or leucine are consumed: eat proteins with leucine after a workout to enhance muscle growth. Another way to trigger MPS is nutrient availability, if BCAAs are consumed in the absence of exercise, MPS occurs . Essentially, muscle growth occurs if you make amino acids available.
Levels of MPS and MPB as Markers of Training Intensity
Recent research has developed methods of tracking exercise intensity by MPS and MPB responses; they are reliable methods considering both phenomenon are of finite duration . The shift in MPB and MPS following a workout is a direct result of the workout intensity: the more intense the workout the larger the shift. Because of the linear timeline, appropriate timing when consuming essential amino acids is critical; consuming a quality protein source less than 30 minutes after a workout is shown to be most effective [1, 2]. And, quality protein should be consumed 48 hours thereafter .
Proteins and Their Leucine Content
A constituent of protein, leucine affects protein metabolism by regulating the translation initiation of protein synthesis, modulating insulin signalling, and providing a nitrogen donor for muscle production of alanine and glutamine . Amounts of leucine vary according to the protein source: an 8 ounce T-bone steak yields 4.3 grams, 8 ounces of chicken breast yields 5.2 grams, a can of tuna yields 3.3 grams, one ounce of chicken liver yields .62 grams, 8 ounces of pork yields around 4.8 grams, one scoop of Optimum Nutrition’s Whey Protein has 2.5 grams, two tablespoons of peanut butter has .48 grams, 1 whole egg (61 grams) has .588 grams, 1 cup of great northern beans yields around 1.1 grams, 1 cup of whole milk has about .64 grams, and 1 cup of quinoa yields .48 grams . The most cost effective source of leucine in the aforementioned list is the whey protein; on top of that, whey has been shown to be as effective as steak, chicken, and pork in fostering lean muscle development. You receive 29 servings of 24 grams of protein with 2.5 grams leucine for about 25 dollars. Standalone BCAAs may be purchased yet are more expensive per serving than protein powders.
There are 9 essential amino acids that must be ingested to grow muscle.
Complete proteins contain all 20 amino acids.
Eating complete proteins without training will cause MPS to increase.
Finding the proper weight and rep range is important to maximize the MPS response.
Although all essential amino acids are important, leucine seems to be the primary determinant in diminishing MPB and increasing MPS following a difficult bout of physical exercise.
MPS and MPB are reliable trackers of exercise intensity.
Protein powders with BCAAs may be the most cost effective way to consume leucine, at around 1 dollar per serving.
Atherton PJ, Smith K. Muscle protein synthesis in response to nutrition and exercise. The Journal of Physiology. 2012;590(Pt 5):1049-1057. doi:10.1113/jphysiol.2011.225003.
Leucine Regulates Translation Initiation of Protein Synthesis in Skeletal Muscle after Exercise; Layne E. Norton and Donald K. Layman
Tipton, Kevin & R. Wolfe, Robert. (2001). Exercise, Protein Metabolism, and Muscle Growth. International journal of sport nutrition and exercise metabolism. 11. 109-32. 10.1123/ijsnem.11.1.109.